title: Glycosaminoglycans mediate retention of the poxvirus type I interferon binding protein at the cell surface to locally block interferon antiviral responses.
abstract: Eradication of smallpox was accomplished 30 yr ago, but poxviral infections still represent a public health concern due to the potential release of variola virus or the emergence of zoonotic poxviruses, such as monkeypox virus. A critical determinant of poxvirus virulence is the inhibition of interferons (IFNs) by the virus-encoded type I IFN-binding protein (IFNα/βBP). This immunomodulatory protein is secreted and has the unique property of interacting with the cell surface in order to prevent IFN-mediated antiviral responses. However, the mechanism of its attachment to the cell surface remains unknown. Using surface plasmon resonance and cell-binding assays, we report that the IFNα/βBP from vaccinia virus, the smallpox vaccine, interacts with cell surface glycosaminoglycans (GAGs). Analysis of the contribution of different regions of the protein to cell surface binding demonstrated that clusters of basic residues in the first immunoglobulin domain mediate GAG interactions. Furthermore, mutation of the GAG-interaction motifs does not affect its IFN-binding and -blocking capacity. Functional conservation of GAG-binding sites is demonstrated for the IFNα/βBP from variola and monkeypox viruses, extending our understanding of immune modulation by the most virulent human poxviruses. These results are relevant for the design of improved vaccines and intervention strategies.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas y Universidad Autónoma de Madrid, Nicolás Cabrera, 1. Campus de Cantoblanco, 28049 Madrid, Spain.
authors.forename: Imma
authors.initials: I
authors.lastname: Montanuy
authors.forename: Ali
authors.initials: A
authors.lastname: Alejo
authors.forename: Antonio
authors.initials: A
authors.lastname: Alcami
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000998:Antiviral Agents / Q000494:pharmacology*; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D015967:Gene Expression Regulation, Viral / Q000502:physiology*; D006025:Glycosaminoglycans / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007372:Interferons / Q000037:antagonists & inhibitors / Q000378:metabolism*; D058977:Molecular Sequence Annotation; D009154:Mutation; D017434:Protein Structure, Tertiary; D014616:Vaccinia virus / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000998:Antiviral Agents; D006025:Glycosaminoglycans; D014764:Viral Proteins; D007372:Interferons